JPH0141340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of drying and sterilizing air.

Conventionally, various air sterilization devices and air drying devices have been used in factories manufacturing foods, medicines, electronic parts, and the like. The present invention provides a novel method for continuously drying and sterilizing air.

The present inventor uses a zeolite as a zeolite, which is a bactericidal agent made of a zeolite solid containing ion-exchanged metal ions having a bactericidal effect, and maintains the water content of this zeolite at 15% by weight or more, preferably 15 to 25% by weight. The inventors have discovered that a high and sustained sterilizing effect can be obtained, and that if the drying step is performed after the sterilization step, air drying and sterilization can be carried out continuously without waste, and the present invention has been completed.

That is, the present invention provides a method for drying and sterilizing air, in which a sterilizing agent consisting of a zeolite-based solid containing ion-exchanged metal ions having a sterilizing effect is provided with a water content of 15% by weight or more, preferably, of the zeolite-based solid. This method is characterized by contacting with air while maintaining the content of the product at 15 to 25% by weight, and then drying.

In the present invention, the bactericidal agent is a natural or synthetic zeolite made of aluminosilicate in which the ion-exchangeable part retains one or more metal ions having a bactericidal effect.

Preferred examples of metal ions with bactericidal effects include Ag,
Examples include Cu and Zn. It is therefore possible to use the above-mentioned bactericidal metals alone or in combination for the above-mentioned purposes.

Zeolite is generally an aluminosilicate with a three-dimensionally developed skeleton structure, and generally has a structure of XM ₂ /nO・Al ₂ O ₃・based on Al ₂ O ₃
It is expressed as ySiO ₂・ZH ₂ O. M represents an ion-exchangeable metal ion, usually a monovalent to divalent metal, and n corresponds to this valence. On the other hand, X and y are the coefficients of metal oxide and silica, respectively, and Z
represents the number of water of crystallization. Many types of zeolites are known, differing in their composition ratio, pore diameter, specific surface area, etc.

The solution of water-soluble salts of metals with bactericidal activity, such as silver, copper, and zinc, used in the present invention easily undergoes ion exchange with zeolite, so using this phenomenon, the above-mentioned metal ions can be extracted singly or It is a mixed type that can be retained in a zeolite stationary phase, but the zeolite particles that retain metal ions have a specific surface area of 150 m ² /g or more,
And it is preferable that the SiO ₂ /Al ₂ O ₃ molar ratio is 14 or less, particularly 11 or less. If not, the bactericidal effect will be poor. This is thought to be due to the small amount of metal ions fixed on the zeolite in a state where they can exhibit their effects. In other words, this is thought to be due to the physicochemical properties of the zeolite, such as the amount of exchange groups, exchange rate, and accessibility.

Therefore, zeolites with a large SiO ₂ /Al ₂ O ₃ molar ratio, known as molecular sieves, are not preferred in the present invention.

In addition, in zeolite with a SiO ₂ /Al ₂ O ₃ molar ratio of 14 or less, it is possible to uniformly retain metal ions that have a bactericidal effect, and for this reason, a high bactericidal effect can be obtained by using such zeolite. It turned out that. In addition, zeolite
The acid and alkali resistance of zeolites with a high silica ratio (SiO ₂ /Al ₂ O ₃ molar ratio exceeding 14) increases with increasing SiO ₂ , but on the other hand, it takes a long time to synthesize, and from an economical point of view, It is not advisable to use zeolites with such high silica ratios. mentioned above
Natural or synthetic zeolites with SiO ₂ /Al ₂ O ₃ ≦14 can be used satisfactorily in the fields in which this structure is normally considered in terms of acid resistance and alkali resistance, and are economically inexpensive. This is a good idea. From this point of view as well, it is convenient that the SiO ₂ /Al ₂ O ₃ molar ratio is 14 or less.

As the zeolite material having a SiO ₂ /Al ₂ O ₃ molar ratio of 14 or less used in the present invention, either natural or synthetic zeolite can be used. For example, natural zeolite is analcime (Analcime).
_SiO2 / _Al2O3 =3.6 _{~ 5.6} ), Chabazite: _SiO2 / _Al2O3 =3.2~6.0 and 6.4~
7.6), Clinoptilolite:
SiO ₂ /Al ₂ O ₃ = 8.5 to 10.5), Erionite (Erionite: SiO ₂ / Al ₂ O ₃ = 5.8 to 7.4), Faujasite (Faujasite: SiO ₂ / Al ₂ O ₃ = 4.2 to 4.6),
mordenite: SiO ₂ /Al ₂ O ₃ = 8.34
~10.0), Philipsite:
SiO ₂ /Al ₂ O ₃ =2.6 to 4.4), and the like. These typical natural zeolites are suitable for the present invention. On the other hand, typical synthetic zeolites include A-type zeolite (SiO ₂ /Al ₂ O ₃ = 1.4-2.4),
-type zeolite (SiO ₂ /Al ₂ O ₃ = 2-3), Y-
_These synthetic _zeolites are suitable as _{the zeolite} material of the _present invention _. . Particularly preferred are
Synthetic A-type zeolite, X-type zeolite, Y
- type zeolites and synthetic or natural mordenites.

The metal ions that perform the bactericidal action in the present invention are
It must be retained in zeolite solid particles through an ion exchange reaction. If it is simply adsorbed or attached without ion exchange, the bactericidal effect and its sustainability will be insufficient. As a method for retaining metal ions, zeolite can be immersed in a metal ion solution using an ion exchange reaction. For example, when converting various zeolites defined in the present invention to the Ag-zeolite of the present invention, a solution of a water-soluble silver salt such as silver nitrate is normally used for Ag-zeolite conversion; Care must be taken not to increase the concentration of For example A-type or X-
When converting type zeolite (sodium type) to Ag-zeolite using ion exchange reaction,
If the silver ion concentration is too high (e.g. 1~
When using 2MAgNO ₃ ), silver ions replace sodium ions in the solid phase through ion exchange, and at the same time, silver oxides etc. are precipitated in the zeolite solid phase.
This has the disadvantage that the porosity of the zeolite is reduced and the specific surface area is significantly reduced. Furthermore, even if the specific surface area does not decrease significantly, the bactericidal activity decreases due to the presence of silver oxide itself. In order to prevent such excess silver from being deposited on the zeolite phase, it is necessary to maintain the concentration of the silver solution in a more dilute state, for example, below 0.3 MAgNO ₃ . The safest concentration of AgNO ₃ is 0.1M or less. When an AgNO ₃ solution with such a concentration was used, the specific surface area of the Ag-zeolite obtained was almost the same as that of the zeolite used as the conversion material, and it was found that the bactericidal effect could be exhibited under optimal conditions.

Next, when the zeolites defined in the present invention are converted to Cu-zeolite, the same phenomenon as that for Ag-zeolite described above occurs depending on the concentration of the copper salt used for ion exchange. For example A-type or
When converting -type zeolite (sodium-type) to Cu-zeolite by ion exchange reaction,
When using 1MCuSO ₄ , Cu ²⁺ replaces Na ⁺ in the solid phase, but at the same time Cu ₃ is added to the zeolite solid phase.
The porosity of zeolite decreases due to the precipitation of basic precipitates such as (SO ₄ )(OH) ₄ , which has the disadvantage that the specific surface area decreases significantly. In order to prevent such excessive copper from being deposited in the zeolite phase, it is preferable to maintain the concentration of the water-soluble copper solution used in a more dilute state, for example, 0.05M or less. When using a _CuSO4 solution with such a concentration, the specific surface area of the Cu-zeolite obtained is almost the same as that of the converted material zeolite,
It was found that this method has the advantage of being able to exhibit its bactericidal effect under optimal conditions.

It was mentioned that when converting to Ag-zeolite and Cu-zeolite, solids may precipitate on the zeolite solid phase depending on the concentration of salts used for ion exchange, but when converting to Zn-zeolite, the salts used This phenomenon is not observed when the distance is around 2 to 3M. Zn usually used in the present invention
- Zeolite can be easily obtained by using salts at concentrations near the above.

When carrying out the ion exchange reaction in a batch method for conversion into the above-mentioned Ag-zeolite, Cu-zeolite and Zn-zeolite, the zeolite material may be immersed in a salt solution having the above-mentioned concentration. In order to increase the metal content in the zeolite material, the number of batch treatments can be increased. On the other hand, when treating a zeolite material by a column method using a salt solution having the above-mentioned concentration, the target metal-
Zeolite is obtained.

The amount of metal in the above metal-zeolite (based on anhydrous zeolite) is 30% by weight or less for silver, and the preferred range is 0.001 to 5% by weight.
It is in. On the other hand, for copper and zinc used in the present invention, metal-zeolite (based on anhydrous zeolite)
The amount of copper or zinc therein is up to 35% by weight, with a preferred range of 0.01 to 15% by weight. Silver,
It is also possible to use copper and zinc ions in combination; in this case, the total amount of metal ions may be 35% by weight or less based on the metal-zeolite (based on anhydrous zeolite), and the preferred range is the composition ratio of metal ions. Although it depends on the amount, it is approximately 0.001 to 15% by weight.

Further, even if metal ions other than silver, copper, and zinc, such as sodium, potassium, calcium, or other metal ions, coexist, the bactericidal effect is not hindered, so the residual or coexistence of these ions is not a problem.

The zeolite containing bactericidal metal ions through ion exchange as described above is in powder form,
Alternatively, it may be in any desired form, such as a pellet formed by solidifying the powder in accordance with a conventional method, or a porous body formed by molding the powder into a porous body with many voids. Alternatively, the zeolite can be a fine powder dispersed and supported within an organic polymer. In this case, the shape of the zeolite ranges from 1 micron to several tens of microns, or several
100 microns, and the organic polymer itself can be in any shape, such as fibrous or granular. Methods for dispersing and supporting the sterilizing metal-containing zeolite within an organic polymer include, for example, adding the zeolite to raw material monomers and mixing them and then polymerizing them, adding them to a reaction intermediate and mixing them, and adding them to the polymer at the end of polymerization. There are a method of mixing, a method of adding and mixing to polymer pellets and molding, and a method of adding and mixing to a dope for molding, such as a spinning stock solution (Japanese Patent Application Laid-Open No. 133235/1983).

The zeolite can also be used in the form of a dispersed support in an organic or inorganic foam capable of finely distributing air.

In the above, it was described that the zeolite-based solid containing bactericidal metal ions in advance is converted into a usage form, but this order is reversed and the zeolite-based solid is first made into a usage form, and then the zeolite-based solid is ionized in the same manner as above. Germicidal metal ions can also be retained in the zeolite by exchange. In this case, zeolite solid particles supported by organic polymers such as fibers can also be sufficiently ion-exchanged (Japanese Patent Application Laid-Open No. 133235/1983).

In the present invention, the bactericidal action of the bactericidal metal ions retained in the zeolite solid is thought to be due to the conversion of oxygen to ozone by the catalytic action of the metal, which oxidizes bacterial enzymes and kills the bacteria. However, it has been found that this bactericidal action is not sufficiently effective unless the zeolite solid contains a certain amount of water. That is, the zeolite solid containing metal ions having a bactericidal effect needs to have a water content of 15% by weight or more, preferably 15 to 25% by weight.

Therefore, in the air drying and sterilization method of the present invention, the drying step must be performed after the sterilization step. Otherwise, a separate means would be required to maintain the moisture content of the zeolite solid particles within the above-mentioned range, and it would be unreasonable that the air once dried would receive moisture again during the sterilization process.

Here, the drying step itself can be performed by a conventionally known method. For example, air can be passed through a column packed with conventional desiccants.

The desiccant is not particularly limited, but for example, zeolite particles, alumina gel particles, activated carbon, silica gel, or a mass formed by adhesively molding these can be used.

In addition, the drying process is operated in a cycle of adsorption, depressurization, purge, and pressurization.
It is also possible to adopt the PSA method.

As shown in FIG. 1, the apparatus for carrying out the method of the present invention is such that air is first passed through a sterilizing column 1 filled with a sterilizing agent, and then air is passed through one of two drying columns. The other drying column 2 is subjected to a regeneration step to remove absorbed moisture. A regeneration step for a sterilizing column filled with a sterilizing agent is rarely necessary in normal use.

Alternatively, as shown in Figure 2, prepare two sterilization/drying columns filled with disinfectant a and desiccant b,
Air is passed through the sterilizer-filled side of one column to sterilize and dry it, while the other column is subjected to regeneration treatment.

As described above, according to the present invention, a method is provided in which sterilization and drying can be carried out continuously and efficiently.

[Brief explanation of drawings]

1 and 2 are flow diagrams of an apparatus for carrying out the method of the present invention, and the numbers in the figures indicate the following: 1: Sterilizing column, 2: Drying column, a: Sterilizing agent, b: Drying agent.

Claims (1)

[Scope of Claims] 1. In a method for drying and sterilizing air, a disinfectant comprising a zeolite solid containing ion-exchanged metal ions having a sterilizing effect has a moisture content of 15% by weight or more. A method characterized by contacting with air while maintaining and then drying. 2. The method according to claim 1, wherein the metal ion having a bactericidal effect is one or more metal ions selected from the group consisting of silver, copper, and zinc. 3 The moisture content of the zeolite solid is 15% by weight or more.
25% by weight. 4. The method according to claim 1, wherein the zeolite solid has a specific surface area of 150 m ² /g or more and a SiO ₂ /Al ₂ O ₃ molar ratio of 14 or less. 5 The zeolite solid is A-type zeolite, X-type zeolite
2. The method of claim 1, wherein the zeolite is comprised of Y-type zeolite, Y-type zeolite, or mordenite. 6. The method according to claim 1, wherein the zeolite solid is formed into a porous body with many voids. 7. The method according to claim 1, wherein the zeolite solid is supported in particulate form and dispersed in the fibers.